it is the single largest gathering of heads of state and gives just in a few hours, president obama, former president george w. bush and hillary clinton sharing air force one, former presidents clinton and carter flying separately, along with presidents and princesses and kings from other countries. many converging on a soccer stadium here in johannesburg, it is built were we're told, for 90,000, may not be big enough. here they come to thank the man who led them to freedom. now how many other figures can you say that about? that they led a country to freedom and showed the world a better way. i had the privilege today of spending time with bono, the band member of u-2, he knew mandela personally and has been a champion for justice since the late '70s. >> when you first heard that he had died, what went through your mind? >> stubborn until the end, you know? it was like he was playing this -- he was trying to outstare god, and finally, god blinked. >> his leadership was in part to get a ability, of not only his consensus, but also his ability to overcome the natural anger and resentf